Respiratory protection devices commonly include a mask body and one or more filter cartridges that are attached to the mask body. The mask body is worn on a person's face, over the nose and mouth, and may include portions that cover the head, neck, or other body parts in some cases. Clean air is made available to a wearer after passing through filter media disposed in the filter cartridge. In negative pressure respiratory protection devices, air is drawn through a filter cartridge by a negative pressure generated by a wearer during inhalation. Air from the external environment passes through the filter medium and enters an interior space of the mask body where it may be inhaled by the wearer.
Various techniques have been used to attach filter cartridges or elements to a respirator. Filter cartridges are commonly connected to an inlet port of a mask body via a threaded engagement, bayonet engagement, or other engagement, for example. In the case of dual cartridge respiratory protection devices, in which two cartridges are provided to filter air for a wearer, the filter cartridges are often connected to air inlets located proximate each cheek portion of the mask, away from a central portion of the mask, such that the cartridges extend outward at sides of the wearer's head. Inhalation check valves are commonly provided for each air inlet, such that air may be delivered from the filter cartridge into the breathing zone through the air inlet away from a central portion, and proximate each cheek portion of the mask body for example.